Method and device for computer numerical control of machining of spectacle lenses

ABSTRACT

The present invention relates to a method and a device for machining glass-lenses using a glass-lens machining apparatus with computerized numerical control. The method of the present invention comprises the following steps: introducing opto-metrical data relating to the glasses support into the computer of the apparatus control device which is provided with a host connection; introducing into the computer the data corresponding to the shape of a selected rim for glasses; introducing into the computer data about the material of the non-machined lens; calculating the required diameter of the glass-lens and displaying the result; introducing a non-machined lens into the apparatus; optionally calculating, e.g. in the host computer, the gradient of a bevel, groove or bezel on the shaped glass-lens according to the data introduced or to the front or back curves which are inherent to the existence of surfaces; and carrying out the computerized numerical-control machining of the non-machined lens.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to computer numerical control (CNC) of spectaclelens machining.

2. Relevant Art

Despite far-reaching automation, known CNC spectacle lens machiningapparatuses, in particular spectacle lens edging machines, require aCNC-controlled particular accuracy, and therefore skill, for example ininserting into the apparatus a lens blank to be machined, and/or aredemanding and complicated to operate as regards inputting the parametersrequired for the spectacle lens machining, which are a function of theoptometric data of the spectacle wearer, the selected spectacle frame,the spectacle lens material and the like.

In the known CNC spectacle lens machining apparatuses, it stills happensthat a finally machined spectacle lens cannot be inserted into theselected spectacle frame, and therefore has to be remachined.

The problem on which the invention is based is to create a method formachining spectacle lenses by means of a CNC spectacle lens edgingmachine, by means of which the operation of the CNC spectacle lensmachining apparatus is simplified and made easier, and by means of whichan increased accuracy is achieved for the shaped spectacle lens.

Furthermore, the invention is based on the problem of improving a CNCspectacle lens machining apparatus such that operation is substantiallysimplified in conjunction with increased machining accuracy.

BRIEF DESCRIPTION OF THE INVENTION

Starting from this formation of the problem, a method is disclosed formachining spectacle lenses by means of a CNC spectacle lens machiningapparatus which comprises, according to the invention, the steps of:

inputting the optometric data of the spectacle wearer, that is to saydioptric number, values and angles of a cylindrical or prismatic cut,intensity and position of a reading portion, into a computer whichcooperates with a control device of the apparatus,

inputting the eye's viewing point or interpupilary distance (PD values)of the spectacle wearer into the computer by means of a selectedspectacle frame,

inputting the shape data of a selected spectacle frame, if appropriateof the profile, the shape and the circumference of a bevel groove of thespectacle frame or of a spectacle lens groove or a spectacle lens dubbedcorner, corresponding to the spectacle frame, into the computer,

inputting the spectacle lens material, that is to say silicate glass orplastic such as CR39 or polycarbonate, into the computer,

calculating the required lens blank diameter in the computer anddisplaying the lens blank diameter,

inserting a lens blank of the desired diameter into the apparatus,

if appropriate, checking the position of the lens blank inserted intothe apparatus, and incorporating the position of the lens blank bycalculation in the machining data,

if appropriate, calculating the profile of a bevel, a groove or a dubbedcorner on the shaped spectacle lens from at least one of the followingparameters: optometric data, PD values, shape data, radii of the frontsurface and rear surface and the center thickness of the spectacle lens,

if appropriate, comparing the shape of the bevel groove in the selectedspectacle frame with the shape of the bevel groove in a spectacle lensedging tool in the machine, and deciding by computation whether themachining of the bevel is or is not possible without or with takingaccount of correction values by computer,

CNC machining of the lens blank, which comprises at least shaping thespectacle lens and, if appropriate, also machining a bevel, a spectaclelens groove or a spectacle lens dubbed corner, if appropriate alsomachining the optical surface(s), it being advantageous that it ispossible for correction values to be incorporated by calculation intothe machining data before the CNC machining of the lens blank as afunction of prescribed machining tolerances, workpiece tolerances andtool tolerances and detected deviations thereof.

In addition to these steps, there can be performed on a screen amonitoring display of the input values and of the required lens blankdiameter, and a positionally accurate imaging of the lens blank and,superimposed thereon, of the shape of the spectacle lens, such that allthe parameters required for the spectacle lens machining can be checkedvisually.

When the bevel groove in the spectacle frame and the bevel resultingfrom the bevel groove in the spectacle lens edging tool are imaged andassigned on the circumference of the spectacle lens on a screen, it isfurther possible for the feasibility of the bevel machining to bechecked visually.

In order to relieve the operator from particular attentiveness and carewhen inputting the parameters, inputting the dats required for spectaclelens machining can preferably be performed in machine-readable form, therequired data can be stored at least partially on at least one datamedium such as a magnetic strip card, bar code card or a floppy disk.

Again, the PD values need not be input alphanumerically into a keyboardwhen the PD values are determined by an automatic video recording systemand the data determined are led directly into the computer of thecontrol device. If the shape data of a selected spectacle frame are notavailable stored on a data medium, the shape data of a selectedspectacle frame, including the bevel profile, the bevel shape and thecircumference, can be determined in a contactless fashion in a scanningdevice and led directly to the computer.

When the dimensions and the shape of the bevel groove in the spectaclelens edging tool are determined in a preferably contactless fashion by avideo recording system or laser scanner system, and these data are leddirectly to the computer, it is possible to use the computer toestablish whether a bevel can be produced on a spectacle lens, which isto be shaped, in accordance with the dimensions and the shape of thebevel groove in the selected spectacle frame with the aid of theexisting spectacle lens edging tool as a function of the wear of thebevel groove in the spectacle lens edging tool, if appropriate withincorporation of a correction value by calculation.

In order to calculate the bevel profile on the circumference of aspectacle lens which is to be shaped, either it is possible for theprofile of the front edge and the rear edge of a spectacle lens, whichis to be shaped, to be scanned in the apparatus, preferably in acontactless fashion by means of a video recording system, whereupon thedata are led directly to the computer, which calculates therefrom theprofile of a bevel suitable for the selected spectacle frame and usesthese values to control the bevel machining; or the profile of the frontedge and of the rear edge of a spectacle lens corresponding to aselected spectacle frame are calculated by the computer using at leaseone of the parameters of: optometric data, PD values, shape data, radiiof the front surface and rear surface and the center thickness, whichcalculates therefrom the profile of a bevel suitable for the selectedspectacle frame and uses these data to control the bevel machining, theprofile of the front edge and of the rear edge can preferably becalculated from the radii of the front surface and rear surface alongwith the center thickness, and/or can be taken over from a computer forthe surface machining. This computer for surface machining can be thesame computer as for the edge machining.

The input and calculated data can be conveyed to a spectacle lensmanufacturer as order data for the lens blank by long-distance datatransmission, such that after the ordered lens blank has arrived, it ispossible to perform the final machining of the lens blank in a spectaclelens machining apparatus attached to the computer.

It is also possible for the input and calculated data to be conveyed toa spectacle lens manufacturer as order data for a finally machinedspectacle lens by means of long-distance data transmission, such thatafter the arrival of the finally machined spectacle lens all that isrequired is for the optician to insert the spectacle lenses into aselected spectacle frame.

All the calculations for determining the machining data can be performedby a host computer which, as an external control unit, controls aplurality of machines and units in multitasking mode.

The solution of the problem mentioned at the beginning is also served bya spectacle lens machining apparatus, having a housing, a machiningchamber in the housing, a spectacle lens holding shaft and a machiningdevice in the chamber, a computer connected to a control device forcontrolling the machining of a lens blank, held by the spectacle lensholding shaft, by means of the machining device, an input keyboardconnected to the computer, and a data reading device, which can beconnected to the control device, for data for the spectacle lensmachining which are stored on a data medium card, such as a magneticstrip card, bar code card or the like.

Moreover, it is possible for there to be present a floppy disk drive,connected to the computer, for data, stored on a floppy disk, for thespectacle lens machining, and/or a scanning device, connected to thecomputer, for the spectacle lens opening in a selected spectacle frameas well as for the profile, the cross-sectional shape and thecircumference of a bevel groove in the spectacle frame, and/or a sensor,connected to the computer, for detecting characterizing markings on alens blank, on packaging for a lens blank or a storage container forlens blanks and/or on a spectacle frame, packaging for a spectacle frameor on a storage container for a spectacle frame, and/or a videorecording system, which can be connected to the control device, forautomatically recording the PD values of the spectacle wearer withreference to a selected spectacle frame, and/or a vertexretractionmeter, connected to the computer, for automatically recordingthe optical values of a shaped spectacle lens or a lens blank, and/or adevice, connected to the computer, for mounting a block or sucker on alens blank or a shaped spectacle lens, and for automaticallytransmitting the position of the block or sucker on the lens blank orthe shaped spectacle lens to the computer, the result being that it issuperfluous for an operator to make alphanumeric inputs into theapparatus.

No particular requirements are made of the accuracy with which the lensblank is inserted into the spectacle lens holding shaft when a detectiondevice, connected to the computer, is present for the position of a lensto be machined with reference to the spectacle lens holding shaft, sincethe position of the lens blank detected by the detection device withreference to the spectacle lens holding shaft can be taken into accountcomputationally when machining the lens blank.

It is likewise possible to provide a detection device, connected to thecomputer, for the diameter of a lens blank, held in the spectacle lensholding shaft and/or for the profile of the front edge and the rear edgeof the circumference of a shaped spectacle lens, the data of which canbe used by the computer to calculate the bevel profile on thecircumference of the shaped spectacle lens and to control the machiningthereof.

When, furthermore, a detection device, connected to the computer, forthe shape and the dimensions of a bevel groove in a spectacle lensedging tool is present, the bevel groove in the spectacle lens edgingtool can be compared with the bevel groove in the selected frame, and adecision can be made as to whether or not a spectacle lens with thecalculated bevel can be inserted into the selected spectacle frame, ifappropriate with incorporation of correction values by calculation as afunction of the shape and the dimensions of the bevel groove in theselected spectacle frame and in the spectacle lens edging tool.

The detection devices for the position of a lens which is to be machinedwith reference to the spectacle lens holding shaft, for the diameter ofa lens blank held in the spectacle lens holding shaft and/or for theprofile of the front edge and the rear edge of the circumference of ashaped spectacle lens, and the detection device for the shape and thedimensions of a bevel groove in a spectacle lens edging tool canpreferably comprise a charge coupled device or CCD camera or a laserscanner system, it being possible for the detection device for thediameter of a lens blank held in the spectacle lens holding shaft and/orfor the profile of the front edge and the rear edge of the circumferenceof a shaped spectacle lens, and the detection device for the shape andthe dimensions of a bevel groove in a spectacle lens edging tool, to beimplemented as separate devices or in a fashion combined from a singledevice.

A screen, connected to the computer, for displaying the input dateand/or for imaging the lens blank with the required diameter and/or thespectacle lens, which is aligned in the correct position with referenceto the lens blank and is to be shaped, and/or the bevel groove crosssection of a selected spectacle frame, as well as the bevel, resultingfrom the dimensions and the shape of the bevel groove of the spectaclelens edging tool, of a spectacle lens to be shaped facilitates thevisual monitoring by the operator with regard to the data which havebeen input or read in, and with regard to the finished spectacle lens,but is not mandatory for the automatic running of the spectacle lensmachining.

When all inputs are performed by means of automatic data reading unitsor scanning devices in the way outlined above, the spectacle lens edgingmachine according to the invention need have only a very simple inputkeyboard, which comprises only a switch-on key, a start key, aninterruption key for the running machining operation, a stop key and, ifappropriate, a key for controlling an aftercut.

BRIEF DESCRIPTION OF THE DRAWING

The invention is explained in more detail below with the aid of anexemplary embodiment illustrated in the single FIGURE of drawing.

DETAILED DESCRIPTION OF THE INVENTION

Of a CNC spectacle lens edging machine which is known per se, the FIGUREillustrates a housing 1 in whose grinding chamber 2 three grindingwheels 3 are arranged on a shaft 4. One of the grinding wheels with acylindrical surface serves for pregrinding the outline of a spectaclelens, while the two further grinding wheels serve for incipientlygrinding different top bevels on the preground spectacle lens. One ofthe bevel grooves is denoted by the reference numeral 12. Arrangedparallel to the shaft 4 with the grinding wheels 3 are coaxial,rotatable, hollow half-shafts 5, 6 of which the half-shaft 6 is axiallydisplaceable. The half-shafts 5, 6 have on their ends annular holdingheads 8 between which a lens blank 9 can be clamped. The clamping can beperformed automatically or via a handle 7. The lens blank 9 can be swunginto the region of the half-shafts 5, 6 by firstly being mounted by handon a holder (not illustrated) on a flap (likewise not illustrated) whichoutwardly seals the grinding chamber 2 and, for example, is held on theholder by means of a controllable suction device which acts outside theregion of the surface required for holding the lens blank 9 between thehalf-shafts 5, 6. Such a device is described in detail in DE 195 37 692C2 of the same applicant.

An illuminating device 11 is arranged in the hollow half-shaft 6, whilea detection device in the form of a CCD camera is arranged coaxiallytherewith in the hollow half-shaft 5. This CCD camera is capable ofpicking up conventional markings, for example a three-point marking 16,illustrated on a screen 14 of the spectacle lens edging machine, on thelens blank 9, and converting them into electric signals. The middlepoint of the three-point marking 16 denotes the optical midpoint of thelens blank 9, while the outer points yield the axial position of acylindrical or prismatic cut.

The signals generated by the CCD camera 10 pass into a transformer 13and are converted there into signals which can be evaluated bycalculation by a computer of a control device 18, such that the image9′, picked up by the CCD camera 10, of the lens blank 9 with themarkings 16 can be represented on the screen 14 in a fashion positionedaccurately with reference to an axis intersection 15.

Accurate positioning of the lens blank 9 is not required, since thevalues picked up by the CCD camera 10 are input via the converter 13into the computer of the control device 18 and are taken into accountthere by calculation when imaging on the screen 14 and during the CNCgrinding of the spectacle lens. The lens blank 9 can therefore bemounted by hand on the holder on the cover, without particularrequirements on the accuracy and skill of the operator, and swungbetween the half-shafts 5, 6, since the position of the optical midpointand the axial position of a cylindrical or prismatic cut are picked upby the CCD camera 10 and taken into account by calculation in thecomputer of the control device 18. The device for detecting the positionof the optical midpoint and the axial position of a cylindrical orprismatic cut on a lens blank 9 between the half-shafts 5, 6 isdescribed in detail in DE 19 52 722 C2 of the same applicant.

The image 9′ of the lens blank 9 on the screen 14 is superimposed in apositionally accurate fashion by an image 17 of the spectacle lens,which is to be form-ground, i.e., edge ground to a specific peripheralshape corresponding to a selected spectacle frame opening, including apossibly required top bevel, such that it is possible when viewing theimage 9′ of the lens blank 9 and the superimposed image 17 of thespectacle lens to establish whether the lens blank diameter issufficient for form grinding of the spectacle lens.

The optometric data of the spectacle wearer, the PD values of thespectacle wearer, the material of the spectacle lens, for examplesilicate glass or plastic such as CR39, polycarbonate and/or the lenscurve data, specifically the radii R₁, R₂ of the optical front surfaceand the optical rear surface, the center thickness of the lens and theroughcast lens diameter can be input, and the type of bevel to beprovided, for example a kaiser bevel, 30% bevel and an image, taken bymeans of a CCD camera 25, of the bevel groove 12 in one of the grindingwheels 3 can be imaged on the screen 14 in a fashion controlled by thecomputer of the control device 18 and, furthermore, in alphanumericform.

A further CCD camera 24 is arranged in the region of the lens blank 9clamped between the half-shafts 5, 6. This CCD camera 24 serves thepurpose of picking up the lens blank diameter and the profile of thefront curve and rear curve on the form-ground spectacle lens as afunction of the angle of rotation of the half-shafts 5, 6, and ofleading them to the control device 18 via the converter 13. Given asuitable arrangement, the CCD cameras 24, 25 can also be combined toform a single CCD camera which optically scans both the lens blank 9 orthe form-ground spectacle lens and the bevel groove 12.

It is also possible to use laser scanner systems instead of the CCDcameras 10, 24, 25.

Connected to the computer of the control device 18 are an input keyboard19, a data reading device 20 for reading in data on data media in theform of a card with a magnetic strip, a bar code or a floppy disk drive21 for reading into the control device 18 data stored on floppy disks, ascanning unit 22 for scanning a spectacle lens opening in a spectacleframe or a pattern disk, and a sensor 23 for reading into the controldevice 18 data recorded on a spectacle lens, a bag for a spectacle lens,on a case with spectacle lens, for example in the form of a bar code, orfor reading data arranged on a spectacle frame in the form of a bar codeinto the control device 18. Furthermore, it is also possible for thereto be connected to the computer of the control device 18 a vertexrefractionmeter 31 which can be used to determine the optometric data ofa given spectacle lens automatically and input them into the computer ofthe control device 18.

The computer of the control device 18, which preferably comprises apersonal computer (PC), constitutes the command center and theoperations planning and scheduling, for an order to be carried out bythe optician. All the data are stored, processed and passed on andcalled up in the computer of the control device. The optometric data ofthe spectacle wearer, that is to say the dioptric number of thespectacle lens, the refracting powers of a cylindrical or prismatic cutas well as the axial position thereof and the corresponding optometricvalues of a reading portion are input into the computer of the controldevice 18 either alphanumerically via the input keyboard 19 or byreading off from a customer card or sickness insurance plan card bymeans of the data reading device 20, inputting a floppy disk into thefloppy disk drive 21, or else by measuring an existing spectacle lens ofthe spectacle wearer by means of vertex refractionmeter 31.

Inputting via a data reading device 20, a floppy disk drive 21 or vertexrefractionometer 31 is preferred, since the input keyboard 19 can inthis case be of particularly simple configuration, and there is a needto use only at most five keys, a key for switching on, a key forinputting the start signal, a key for controlling an aftercut, a key foraborting or interrupting a grinding operation, and a stop key. Again,the shape data of the spectacle lens opening of a selected spectacleframe can be input into the control device 18 via the data readingdevice 20 or the floppy disk drive 21 when these data are present in aform stored on a card or a floppy disk, for example supplied by thespectacle frame manufacturer together with the spectacle frame.

If this is not the case, the spectacle frame opening of a selectedspectacle frame can be scanned by means of a scanning device 22. Thisscanning can preferably be carried out in a contactless fashion, forexample by means of a video scanning system such as is described in DE40 19 866 A1 of the same applicant. This video scanning system can beused to pick up the spectacle lens opening, including the profile of thebevel groove in a three-dimensional fashion including thecross-sectional shape, and to input them into the computer of thecontrol device 18.

The pupil distance and the position of the pupils with reference to aselected spectacle frame (PD values) can be determined either in theusual way by the optician and input alphanumerically into the computerof the control device 18 via the keyboard 19, or the PD values arepicked up by means of a video system 28 from the spectacle wearer withthe aid of a mounted, selected spectacle frame, and evaluated and feddirectly to the computer of the control device 18. Such a video systemis known under the name of “Video-Infral” from Rodenstock AG.

Although, as described above, the lens blank 9 is preferably swung-inbetween the half-shafts 5, 6 without the use of a block, it is alsopossible to provide a lens blank 9 in the block device 29 with a blockwhich is arranged at the optical midpoint and can be used to insert thelens blank between the half-shafts 5, 6 in an accurately positionedfashion without the need for renewed checking of the position of theoptical midpoint with reference to the axis of rotation of thehalf-shafts 5, 6. In this case, the block device 29 can be configured asdescribed in DE 42 33 400 C2 of the same applicant and connected to thecomputer of the control device 18, and this block device can alsocontrol the imaging of the image 9′ of the lens blank 9 and of thespectacle lens 17 on the screen 14 via the computer of the controldevice 18.

Using the optometric data input into the computer of the control device18, the spectacle frame data, the PD values and the further customerdata, the computer of the control device 18 can calculate a lens blankwith regard to the required diameter, the radii R₁, R₂ of the opticalfront surface and rear surface, and the optical center thickness as afunction of the type of the spectacle lens material, that is to sayplastic or silicate glass, and feed them via a modem 26 to a spectaclelens manufacturer for the purpose of ordering lenses.

The lens curve data R₁ and R₂ and the center thickness can also be inputinto the computer of the control device 18 by means of the inputkeyboard 19, or by means of a bar code on the lens blank itself or on alens blank container. The computer of the control device 18 uses theinput data to calculate the shape data for form grinding the lens blank19 in accordance with the shape of the spectacle lens, which is yieldedby the selected spectacle frame, and thereby controls the form grindingby means of the grinding wheels 3.

In order to grind the bevel, the computer of the control device 18 usesthe spectacle frame data and the lens blank data to calculate a bevelprofile, which can, for example, correspond exactly to the profile andthe circumference of the bevel groove in the selected spectacle frame.It is likewise possible to specify a bevel profile, for example a 30%bevel, and the computer in the control device 18 checks whether thisprescribed bevel profile is possible with the prescribed lens blank, andcorresponds with reference to its circumference to the circumference ofthe bevel groove in the selected spectacle frame. If this is not thecase, the computer in the control device 18 carries out a correction,for example by displacing the bevel profile, after which the bevel cutis carried out.

It is also possible to use the CCD camera 24 to measure the space curveof the front edge and the rear edge of the form-ground spectacle lens inthree dimensions, and to lead them to the control device 18 via theconverter 13. The computer in the control device 18 can use these datato calculate a bevel profile which is, for example, formed from the meanvalue of the profile of the front edge and the rear edge of theform-ground spectacle lens, or is at a constant distance from the frontedge.

Instead of the CCD camera 24, it is also possible to provide amechanical scanning system for the profile of the front edge and therear edge of the form-ground spectacle lens, and for the contour of theform-ground spectacle lens, to which there are connected appropriateconverters for generating electric signals which can be picked up andprocessed by the control device 18. Such electromechanical scanningdevices for the profile for the front edge and the rear edge of theform-ground spectacle lens and of the contour of a form-ground spectaclelens having desired/actual value comparison are described in DE 42 08835 C2 and DE 43 20 934 C2 of the same applicant. The profile of thefront edge and the rear edge can also be calculated from the radii ofthe front surface and rear surface and the center thickness, and/or betaken over from a computer for surface machining. This computer forsurface machining can be the same computer as for the edge machining.

The bevel groove 12 picked up by the CCD camera 25 is compared in thecomputer of the control device 18 with the image of the bevel groovepicked up by means of the spectacle frame scanning device 22. It ispossible by means of this comparison for the computer of the controldevice 18 either to give the control command to grind the bevel on thespectacle lens when the bevel grooves correspond, or the correct thegrinding of the bevel when the deviation between the bevel groove 12 inthe grinding wheel and the bevel groove in the spectacle frame does notexceed a prescribeable value, or to abort the grinding operation whenthe deviation is outside the prescribed tolerance.

It is also possible to connect to the computer of the control unit 18 ahost computer 30 which then undertakes the calculations externally andcan control a plurality of machines and units in multitasking mode.

The method according to the invention and the device for machiningspectacle lenses can therefore be used firstly to scan a selectedspectacle frame in a contactless fashion with the aid of imageevaluation, the values r=f(γ) and z=f(γ), and the circumference U beingdetected, in which case r is the radius of the spectacle frame openingas a function of the angle γ, z is the coordinate in a directionperpendicular to the plane of the spectacle frame, and U is thecircumference of the bevel groove. In addition, the shape of the bevelgroove is also determined as a function of γ and compared with thecontactless measurement of the bevel groove in the grinding tool. Theaim is to determine correction values during grinding in advance, evenif the bevel groove of the grinding tool does not correspond to thebevel groove of the spectacle frame.

Moreover, the lens blank is measured, including the circumferences inaccordance with its markings in a contactless fashion, and ground,preferably without a block, in the apparatus by using the computer toassign the frame shape to the position of the lens blank between thehalf-shafts 5, 6, including prescribed decentration (PD) values.

After the measurement of the position, the shape and the marking bymeans of a device permanently assigned to the apparatus, which can alsobe arranged in the apparatus itself, the spectacle lens no longer needsto be picked up by hand since, furthermore, the profile of the spacecurve of the front edge z₁=f(γ) and the rear curve z₂=f(g) is measuredin a contactless fashion in the apparatus, and the profile of the bevelcurve is determined in the computer and used to control the grindingoperation.

Consequently, after insertion of the lens blank up to the finishing ofthe form-ground spectacle lens provided with a bevel, the spectacle lensis no longer taken out of the apparatus, with the result that nodeviations can accumulate from step to step.

If, by contrast, faults should occur during machining of spectaclelenses, it is possible to use a modem 27 to make contact with themanufacturer of the apparatus, who is able in this way to use a testprogram to test the computer of the control device 18, with allconnected input devices, and the spectacle lens edging machine, and tocreate a fault diagnosis which is conveyed back to the optician andprovides him with information on the screen 14 as to how the faults canbe remedied, and/or whether the apparatus needs to be repaired.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It isintended therefore, that the present invention not be limited by thespecific disclosure herein, but to be given the full scope permitted bythe appended claims.

What is claimed is:
 1. A method of computer numerically controlled (CNC)spectacle lens machining comprising the steps of: inputting optometricdata of a spectacle wearer, including diopter number, values and anglesof a cylindrical or prismatic cut, and power and position of a nearportion, to a computer associated with a control unit of a lensmachining apparatus; inputting an interpupillary distance (PD) value tothe computer corresponding to a selected spectacle frame; inputting datato the computer representing the shape of the selected spectacle frame,and the curvature, shape, and periphery of a bezel of the selectedspectacle frame inputting data to the computer identifying the materialof a selected spectacle lens; computing a required lens blank diameterfrom the inputted data; visually displaying the lens blank diameter;inserting a lens blank of the required diameter into the lens machiningapparatus; computing the curvature of a bevel on the spectacle lens tobe machined from one or more of the optometric data, PD values, shapedata, radii of the front or back surface, and center thickness of thespectacle lens; generating CNC machining data based on the computedcurvature; comparing data characterizing the bezel of the selectedspectacle frame with data characterizing a portion of a spectacle edgecutting tool in the machining apparatus and determining from thecomparison if machining of a required bevel is possible, and if so, ifany correction to the CNC machining data is required; if correction ofthe CNC machining data is required to permit machining of the bevel,determining required correction values for the machining data as afunction of predetermined machining, workpiece and tool tolerances, andestablished deviations, and incorporating the correction values in themachining data; CNC machining of the lens blank according to themachining data with any incorporated correction values to form theperipheral shape and bevel of the lens.
 2. A method in accordance withclaim 1, further including the step of machining one or both opticalsurfaces of the lens blank.
 3. A method in accordance with claim 1,further including the steps of: computing the curvature of the frontedge and the rear edge of a spectacle lens shape by the computer for aselected spectacle frame from one or more of the optometric data, PDvalues, shape data, radii of the front and back surface, and centerthickness; calculating the curvature of a bevel suitable for theselected spectacle frame from the computed front and rear edgecurvature; and controlling the bevel machining based on the calculatedbevel curvature.
 4. A method in accordance with claim 1, furtherincluding the steps of: checking the position of the lens black insertedin the machine; and employing of the position of the lens blank ingenerating the machining data.
 5. A method in accordance with claim 4,further including the steps of displaying the inputted values, therequired lens blank diameter, and a positionally correct image of thelens blank with the spectacle lens shape superimposed thereon on adisplay device.
 6. A method in accordance with claim 1, in which thebezel in the spectacle frame and the bevel on the periphery of thespectacle lens resulting from the bezel in the spectacle lens machiningtool are imaged and associated on a display device.
 7. A method inaccordance with claim 1, in which the data required for the spectaclelens machining is inputted in machine-readable form.
 8. A method inaccordance with claim 7, in which the required data is at leastpartially stored on at least one data storage medium.
 9. A method inaccordance with claim 1, in which the PD values are determined by anautomatic video recording system, and the resulting data are transmittedto a computer.
 10. A method in accordance with claim 1, in which theshape data of a selected spectacle frame, including the bezel curvature,the bezel shape, and the periphery are determined without contact in ascanning device and transmitted to the computer.
 11. A method inaccordance with claim 1, in which the dimensions and the shape of thebezel in the spectacle edge machining tool are determined withoutcontact by a video recording system or laser scanner system, and theresulting data are transmitted to the computer.
 12. A method inaccordance with claim 1, in which the curvature of the front edge andthe rear edge is computed from the radii of the front and back surfacesand the center thickness and/or is obtained from a computer whichcontrols surface machining of the lens.
 13. A method in accordance withclaim 1, in which the inputted and computed data are transmitted bytelecommunication to a spectacle lens manufacturer as data for orderinga lens blank.
 14. A method in accordance with claim 13, in which theordered and received lens blank is finish-machined in a spectacle lensmachining machine connected to the control unit.
 15. A method inaccordance with claim 1, in which the inputted and computed data aretransmitted by telecommunication to a spectacle lens manufacturer at aremote location as data for ordering a finish-machined spectacle lens.16. A spectacle lens machining apparatus comprising: a housing; amachining chamber in the housing including therein a spectacle lensholding shaft and an installed edge machining tool; a computer-operatedcontrol device for controlling the machining by the edge machining toolof a lens blank held by the spectacle lens holding shaft; an inputkeyboard connected to the computer, a data reading device connected tothe computer for reading spectacle lens machining data stored on a datastorage medium, and/or a scanning unit connected to the computer forscanning the spectacle lens opening in a selected spectacle frame andthe curvature, cross-sectional shape, and periphery of a bezel in thespectacle frame, and a recognition device connected to the computer andoperative to recognize the shape and dimensions of a bezel in theinstalled spectacle lens edge machining tool, the computer beingoperative to: generate CNC machining data; compare data characterizingthe shape of the bezel in the selected spectacle frame with datacharacterizing a portion of the shape of the edge machining tool;determine from the comparison if machining of a required bevel ispossible with the edge machining tool, and if so, if any correction tothe CNC machining data is required; if correction of the CNC machiningdata is required to permit machining of the bevel, determine requiredcorrection values for the machining data as a function of predeterminedmachining, workpiece and tool tolerances, and established deviations,and incorporate the correction values in the machining data; and operatethe control device to machine the lens blank according to the machiningdata including any required correction values to form the peripheralshape and bevel for the lens.
 17. A spectacle lens machining apparatusin accordance with claim 16, further including a disk drive connected tothe computer, and operative to read spectacle lens machining data storedon a floppy disk.
 18. A spectacle lens machining apparatus in accordancewith claim 16, further including a sensor connected to the computeroperative to recognize characterizing identification markings associatedwith a lens blank, and/or a spectacle frame.
 19. A spectacle lensmachining apparatus in accordance with claim 18, wherein the sensor isoperative to read the characterizing identification markings from a lensblank, from a package for a lens blank, or from a storage container fora plurality of lens blanks.
 20. A spectacle lens machining apparatus inaccordance with claim 18, wherein the sensor is operative to read thecharacterizing identification markings from a spectacle frame, a packagefor a spectacle frame, or a storage container for a plurality ofspectacle frames.
 21. A spectacle lens machining apparatus in accordancewith claim 16, further including a video recording system connected tothe computer which is operative to automatically record the PD values ofa spectacle wearer from inspection of a selected spectacle frame.
 22. Aspectacle lens machining apparatus in accordance with claim 16, furtherincluding a lens meter connected to the computer which is operative toautomatically record the optical values of a peripherally shapedspectacle lens or of a lens blank.
 23. A spectacle lens machiningapparatus in accordance with claim 16, further including a deviceconnected to the computer which is operative to attach a block orsuction device to a lens blank or on a peripherally shaped spectaclelens, and to automatically transmit the position of the attached blockor suction device to the computer.
 24. A spectacle lens machiningapparatus in accordance with claim 16, further including a recognitiondevice connected to the computer which is operative to recognize theposition of a lens blank to be machined with respect to the spectaclelens holding shaft.
 25. A spectacle lens machining apparatus inaccordance with claim 24, wherein the recognition device is a CCDcamera.
 26. A spectacle lens machining apparatus in accordance withclaim 16, further including a recognition device which is operative todetermine the diameter of a lens blank held in the spectacle lensholding shaft and/or the curvature of the front edge and rear edge ofthe periphery of a periphery shaped spectacle lens.
 27. A spectacle lensmachining apparatus in accordance with claim 26, wherein the recognitiondevice is a CCD camera.
 28. A spectacle lens machining apparatus inaccordance with claim 16, further including a display device connectedto the computer, and wherein the computer is operable to display one ormore of: the inputted data; an image of the lens blank having therequired diameter for a spectacle lens or a desired peripheral shape; aspectacle lens having a desired peripheral shape which has thepositionally correct alignment with respect to the lens blank, the bezelcross section of a selected spectacle frame, and of the bevel of aspectacle lens having a desired peripheral shape to be machined, which(bevel) results from the dimensions and the shape of the bezel of aninstalled edge machining tool.
 29. A spectacle lens machining apparatusin accordance with claim 16, further including an input keyboard, whichhas only an on/off key, a start key, a key for interrupting a machiningoperation in progress, and a stop key.
 30. A spectacle lens machiningapparatus in accordance with claim 16, further including an inputkeyboard, which has only an on/off key, a start key, a key forinterrupting a machining operation in progress, a stop key, and a keyfor controlling a regrinding operation.